In this study, the prevalence of canine helminthiases in Kigali city was 39.8% ±5.08. The dog’s age (1 to 2. 5 years old and at least 5 years old) and location (Gasabo and Kicukiro) were statistically significant risk factors associated with the canine helminthiasis. Our findings can help policy makers to strategize effective control measures in dog populations and to inform dog owners of the role of dogs in transmitting zoonotic helminthiases to other animals and to humans.
The study overall prevalence of 39.8±5.08 was lower but comparable to 51.7% reported by Idika et al. [23] in Nigeria. However, it was much lower than 75.26% and 91.4% reported by Abere et al. [13] in Ethiopia and Davoust et al. [24] in Gabon, respectively. Management practices and climatic conditions might have influenced difference in prevalence in these various studies. Around 46.2% of dogs involved in this study were regularly or irregularly dewormed, while 83.9% ate food provided by the owners. However, majority of the dogs investigated by Davoust et al. in Gabon did not receive veterinary care including deworming. Abere et al. [13] conducted their study in Bahir Dar town, and the latter borders lake Tana and Blue Nile. The influence of these waterbodies on the weather of the region would influence the biology of helminths.
Again, Rwanda is located in the equatorial belt, but it has a modified humid climate including rainy forest and savannah types [25]. However, Gabon has a typical equatorial climate [24]. The climate can influence the biology of helminths and parasites at large. For instance, temperature (warm or cold), precipitation, and relative humidity can favour or impair the hatchery of helminth eggs or the development of larvae into mature worms. Again, the biology of intermediate hosts can be affected by extreme temperatures. For example, extreme temperatures can shrink habitats for snails (intermediate hosts for trematodes). Such temperatures can also influence breeding season for mosquitoes (vectors for filarial nematodes) [26,27].
This study prevalence of Ancylostoma spp (32.3 ±4.85) was comparable to 34.8% found by Davoust et al. [24] in Gabon. However, it was higher than 24.6% reported by Ayinmode et al. [28] in Nigeria, and lower than 93.8% reported by Schandevyl et al. [29] in Zaϊre (currently the Democratic Republic of Congo). Difference in prevalence may be related to management practices and accuracy in coprological testing. For instance, the majority of dogs involved in the study by Schandevyl et al. [29] in the Democratic Republic of Congo were not properly looked after and they all were in poor condition. Furthermore, Schandevyl et al. [29] performed both McMaster technique and larval culturing to detect Ancylostoma spp.
Different species of Ancylostoma can infect dogs including A. caninum, A. braziliense, A. ceylanicum and Uncinaria stenocephala [30]. Of these, A. braziliense, A. caninum and U. stenocephala can cause cutaneous larva migrans (sand-worm disease) in humans, while A. ceylanicum is able to cause eosinophilic enteritis. Similarly, A. caninum has been reported to cause eosinophilic enteritis, but it rarely matures into adult in human small intestine [31,32]. Studies conducted in Rwanda reported human ancylostomosis prevalence that varies between 6.33% and 33% [33,34].
In this study, 38.7% (12/31) of dogs that were infected with Ancylostoma or Toxocara had a high level of infection (EPG ≥ 550) and developed mono-infection caused by Ancylostoma spp. These dogs could shed a high number of the eggs in the environment and potentially put people at risk of contracting hookworm disease. Given the challenges to distinguish species of Ancylostoma based on egg morphometry and that a host can be parasitised by several species concurrently [30], the investigation of human ancylostomosis in Rwanda should take into consideration the zoonotic aspect, thus, the collection of information about pet ownership by human patients could guide the diagnosis.
The prevalence of cestodes (6.5±2.55) was lower than 8.6 % reported by Davoust et al. [24] in Gabon. It was however higher than 2.7% reported by Schandevyl et al. [29] in the Democratic Republic of Congo. Dogs can harbour zoonotic cestodes, among others, Echinococcus spp and Dipylidium caninum [31].
The prevalence of Toxocara canis in the present study was 1%; lower than 9.8% reported by Ayinmode et al. [28] in Nigeria. Toxocara canis antibodies have been detected in people across Africa. For instance, two previous studies conducted in preschool children aged between 9 months to 5 years old in Nigeria and in children aged 1-15 years old in Ghana detected Toxocara canis antibodies in 37.3% and 53.5% of the study children, respectively [35,36]. Further, one study conducted in various groups of professionals in Egypt detected anti-T. canis antibodies in 24% of the professionals [37]. Although there are no published data on the situation of human toxocariasis in Rwanda, the EPG of faeces of the dog suffering from Toxocarosis and Ancylostomosis in this study, had an EPG of 750 for Toxocara canis. The high level of infection in tested dog (EPG ≥ 550) suggests that the dog could shed a high number of eggs in the environment and potentially put people at risk of developing toxocariasis.
Similar to a previous study by Idika et al. [23] in Nigeria, this study found that dog’s age correlates positively with the prevalence of helminthiases (all odds ratios increase for age groups above 1 year. The present study also found a direct correlation between dog’s location and the prevalence of canine helminthiases. Difference in management practices across study sites might have influenced the prevalence of canine helminthiases. For example, 50.5% of the sampled dogs were in Nyarugenge district and part of the three sectors selected across Nyarugenge was suburban. The sampled dogs from Gasabo and Kicukiro districts accounted for 20.5% and 29% respectively and part of study area across the districts was urban. In addition, majority of dogs fed on food cooked for them and of scavenging dogs was in urban and suburban study sites, respectively.
have impacted the prevalence of canine helminthiases. Thus, the data in this study is a snapshot prevalence which may not necessarily represent the true burden of canine helminthiases. A kinetic study could shed some light on the prevalence and the dynamics of the helminthiases in dogs Due to limited resources, researchers could not fully investigate the main canine helminths. Further studies using molecular laboratory technique would be most welcome.
The results of the binary logistic regression analysis showed unusually wide 95% confidence intervals of the odds ratios, especially for the dog’s age, and location. This can largely be attributed to excessively small sample sizes for some age groups and districts as well as inconsistency in location data [38]. For example, the sample of infected dogs that were aged < 1 year and ≥ 5 years were only 2 and 9 dogs, respectively. Consistency in location data also appears to be a cause of wide confidence intervals for district covariate. The district of Gasabo had smaller samples for both infected and non-infected dogs.